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Cubic spline predistortion, algorithm and training, for a wireless LAN system

a wireless lan system and cubic spline technology, applied in data switching networks, instruments, high-level techniques, etc., can solve problems such as loss of transmit modulation accuracy, cost of output power and pa efficiency, and spectral regrowth

Inactive Publication Date: 2005-04-19
VALTRUS INNOVATIONS LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0007]The present invention includes methods and devices to apply predistortion to correct nonlinearities of a power amplifier in an OFDM symbol transmission system. According to one aspect of the invention, attention is paid to clipping of symbols and to matching an effective input range of the predisto

Problems solved by technology

A major challenge in OFDM transceiver design is ensuring the linearity of the transmitter and particularly the RF power amplifier (PA).
This non-linearity causes spectral regrowth due to intermodulation products and loss in transmit modulation accuracy.
The typical approaches to PA non-linearity are to either increase the power backoff (i.e. decreasing the input range to the PA such that the PA operates in its more linear region) at the cost of output power and PA efficiency or to use a more linear and consequently more expensive PA.
Unfortunately, due to the design constraints imposed by 802.11a compliance, the performance of PAR reduction techniques alone is not anticipated to be very significant.

Method used

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  • Cubic spline predistortion, algorithm and training, for a wireless LAN system
  • Cubic spline predistortion, algorithm and training, for a wireless LAN system
  • Cubic spline predistortion, algorithm and training, for a wireless LAN system

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Embodiment Construction

[0031]The following detailed description is made with reference to the figures. Preferred embodiments are described to illustrate the present invention, not to limit its scope, which is defined by the claims. Those of ordinary skill in the art will recognize a variety of equivalent variations on the description that follows.

Glossary and Nomenclature

[0032]Many symbols are used in this application, so their meanings are set out here for reference.

[0033]

AMAmplitude ModulationBPSKBinary Phase Shift KeyingcdfCumulative Distribution FunctionCDMACode Division Multiple AccessD / ADigital to Analog converterFFTFast Fourier TransformGaAsGalium Arsinide (in reference to type of PA)IEEEInstitute of Electrical and Electronic EngineersIFIntermediate FrequencyIFFTInverse Fast Fourier TransformOFDMOrthogonal Frequency Division MultiplexingOSROver Sample RatePAPower AmplifierPARPeak to Average RatioPBOPower Back-OffPDPre-distortionpdfProbability Density FunctionPMPhase ModulationPSDPower Spectral Dens...

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Abstract

The present invention includes methods and devices to apply predistortion to correct nonlinearities of a power amplifier in an OFDM symbol transmission system. More particularly, predistortion is patterned to take into account clipping of symbols and to match an effective input range of the predistorter with an average power output of the power amplifier. This invention may be applied to a variety of standards utilizing OFDM technology, including IEEE 802.11a, Hiperlan / 2 and MMAC.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is related to the commonly owned, U.S. patent application Ser. No. 10 / 259,082, filed Sep. 27, 2002, entitled “Gain and Phase Imbalance Compensation for OFDM Systems” by the same inventor. The related application is hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]The present invention includes methods and devices to apply predistortion to correct nonlinearities of a power amplifier in an OFDM symbol transmission system. More particularly, predistortion is patterned to take into account clipping of symbols and to match an effective input range of the predistorter with an average power output of the power amplifier. This invention may be applied to a variety of standards utilizing OFDM technology, including IEEE 802.11a, Hiperlan / 2 and MMAC.[0003]A major challenge in OFDM transceiver design is ensuring the linearity of the transmitter and particularly the RF power amplifier (PA). The PA has a maximum output...

Claims

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Application Information

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IPC IPC(8): G01R19/00H03F1/32H04L12/28H04L12/56H04L27/26
CPCH03F1/3241H04W28/18H04L27/2626H04W84/12H04L27/2623Y02D30/70
Inventor MUELLER, A. JOSEPH
Owner VALTRUS INNOVATIONS LTD
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